EP0371695B1 - Liquid crystal device for providing a spatial light modulator for modulating a laser beam - Google Patents

Liquid crystal device for providing a spatial light modulator for modulating a laser beam Download PDF

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Publication number
EP0371695B1
EP0371695B1 EP89312169A EP89312169A EP0371695B1 EP 0371695 B1 EP0371695 B1 EP 0371695B1 EP 89312169 A EP89312169 A EP 89312169A EP 89312169 A EP89312169 A EP 89312169A EP 0371695 B1 EP0371695 B1 EP 0371695B1
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Prior art keywords
liquid crystal
crystal device
micro
electrodes
metres
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German (de)
English (en)
French (fr)
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EP0371695A2 (en
EP0371695A3 (en
Inventor
Tadao C/O Seiko Instruments Inc. Iwaki
Hiroshi C/O Seiko Instruments Inc. Kuroda
Junko C/O Seiko Instruments Inc. Yamanaka
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Seiko Instruments Inc
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Seiko Instruments Inc
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133553—Reflecting elements
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/42—Mixtures of liquid crystal compounds covered by two or more of the preceding groups C09K19/06 - C09K19/40
    • C09K19/46—Mixtures of liquid crystal compounds covered by two or more of the preceding groups C09K19/06 - C09K19/40 containing esters
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1339—Gaskets; Spacers; Sealing of cells
    • G02F1/13394—Gaskets; Spacers; Sealing of cells spacers regularly patterned on the cell subtrate, e.g. walls, pillars
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1343—Electrodes
    • G02F1/134309—Electrodes characterised by their geometrical arrangement
    • G02F1/134336—Matrix
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference
    • G02F1/216—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference using liquid crystals, e.g. liquid crystal Fabry-Perot filters
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1339—Gaskets; Spacers; Sealing of cells
    • G02F1/13392—Gaskets; Spacers; Sealing of cells spacers dispersed on the cell substrate, e.g. spherical particles, microfibres
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/139—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
    • G02F1/1396—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent the liquid crystal being selectively controlled between a twisted state and a non-twisted state, e.g. TN-LC cell
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/139—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
    • G02F1/141—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent using ferroelectric liquid crystals

Definitions

  • the present invention relates to a liquid crystal device for providing a spatial light modulator for modulating a laser beam.
  • Liquid crystal devices capable of electrically modulating a laser beam have often been used experimentally as liquid crystal displays in liquid crystal televisions.
  • the resolution offered by any of the conventional liquid crystal devices, which have been tried, remains as low as 2lp/mm to 2.5 lp/mm. Consequently, such conventional liquid crystal devices have failed to satisfy conditions, including a resolution of 10 lp/mm to 100 lp/mm, necessary for optical data processing.
  • the contrast ratio is as low as 1/5 to 1/20, which does not meet the requirements, including a contrast ratio of 1/100 to 1/1000, necessary for optical data processing.
  • the wave front distortion after laser beam modulation becomes greater as a result of the inferior flatness of the substrate. Consequently, the wave front needs correcting, using matching oil, a phase conjugate wave or the like.
  • Document EP-A-0260073 discloses a liquid crystal device comprising transparent substrates, electrode structures, alignment layers and dielectric multi-layer film mirrors.
  • Document US-A-4448491 discloses a liquid crystal device comprising transparent substrates, electrode structures and a plurality of insulators which act to maintain the thickness of the liquid crystal layer.
  • a liquid crystal device comprising a first transparent substrate, which has a flatness of 0.05 micro-meters or less, having formed thereon a first dielectric multi-layer film mirror, a first electrode structure and a first alignment layer; a second transparent substrate, which has a flatness of 0.05 micro-meters or less having formed thereon a second dielectric multi-layer film mirror, a second electrode structure, and a second alignment layer; a liquid crystal layer between the first and second substrates; and gap control means for ensuring a uniform gap between the substrates with the gap control means comprising a plurality of insulating films having a thickness in the range of 1.5 micro-meters to 6.0 micro-meters formed on the inward facing side of the first transparent substrate and/or the second transparent substrate.
  • the present invention as described below provides a liquid crystal device having a high contrast necessary for optical data processing.
  • the liquid crystal device as described also meets the requirements of a high resolution necessary for optical data processing.
  • the wave front distortion is extremely low after light modulation.
  • the preferred liquid crystal device has a pair of glass substrates having a flatness of 0.05 micro-meters and less, dielectric multi-layer film mirrors having a reflectivity of fifty percent and over, a plurality of transparent electrodes arranged in a matrix, a plurality of metal electrodes connecting rows and columns respectively of the transparent electrodes a pair of alignment layers, insulating films, and a liquid crystal layer.
  • the contrast of the liquid crystal device becomes even in the display area.
  • the dielectric multi-layer film mirrors are formed on the inner faces of the glass substrates so as to constitute a Fabry-Perot etalon via the liquid crystal layer and so as to enhance the contrast ratio.
  • the metal electrodes efficiently supply each of the transparent electrodes with electric signals, and each of the transparent electrodes has a junction electrode and a picture element electrode, so that the electric signal is efficiently applied to the liquid crystal material of the picture element, and the liquid crystal device attains a high resolution.
  • the insulating films are arranged in a matrix to provide a uniform gap between the glass substrates.
  • FIG. 1 and Figure 2 show an electrode structure of a liquid crystal device embodying the present invention.
  • the liquid crystal device is formed by injecting a liquid crystal material 6 between glass substrates 1a, 1b which carry opposed transparent electrodes 3a, 3b.
  • the glass substrate 1b has formed sequentially on its inner face a dielectric multi-layer film mirror 2b, the transparent electrodes 3b, metal electrodes 4b, and an SiO film 7b.
  • the glass substrate 1a has formed sequentially on its inner face a dielectric multi-layer film mirror 2a, transparent electrodes 3a, metal electrodes 4a, insulating films 5 and an SiO film 7a.
  • the transparent electrodes 3a, 3b are arranged in a matrix, and each pair of the transparent electrodes 3a, 3b has associated therewith a junction electrode 8 and a picture element electrode.
  • the metal electrodes 4a are arranged in parallel, and each of the metal electrodes 4a is connected to a column of the transparent electrodes 3a through the junction electrodes 8.
  • the metal electrodes 4b are also arranged in parallel, and each of the metal electrodes 4b is connected to a row of the transparent electrodes 3b through the junction electrodes 8.
  • the metal electrodes 4a, 4b intersect at right angles as illustrated in Figure 2.
  • the insulating films 5 are arranged in a matrix on the metal electrodes 4a on the glass substrate 1a, and control the spacing between the glass substrates 1a, 1b.
  • the glass substrates 1a, 1b may be made of an ordinary glass, such as soda glass and borosilicate glass, an optical glass, such as flint glass and crown glass, or a quartz glass.
  • An optical glass known as BK7 is used in this embodiment.
  • the flatness of the glass substrate is set to have a variation not greater than 0.05 micro-metres within a data display area. When the flatness variation of the glass substrate was made greater than 0.05 micro-metres in visible light, the contrast of the liquid crystal device according to the present invention was seen to become conspicuously uneven. A flatness variation of not greater than 0.05 micro-metres is therefore preferred.
  • Each of the dielectric multi-layer film mirrors 2a, 2b is prepared by the alternate formation by vacuum deposition of two or three kinds of dielectric thin films having different refractive indexes.
  • An [HL] N L/glass substrate had a well known dielectric multi-layer film mirror structure, where H is a ⁇ /4 film of high refractive material, L is a ⁇ /4 film of low refractive material, ⁇ is the wavelength of a laser beam to be used, and N is an integer not smaller than 4.
  • [HL] N in this case means the [HL] structure is repeated N times.
  • the transparent electrodes 3a, 3b which are ITO electrodes as thick as approximately 1200 Angstroms, are formed by vacuum deposition. However, sputtering may be used for the formation of the ITO electrodes. Moreover, any value ranging from 200 Angstroms to 2000 Angstroms may optionally be selected as the film thickness of the ITO electrodes, providing this gives desired electrical characteristics, although this is dependent on the film forming conditions.
  • the metal electrodes 4a, 4b which have a thickness of 1800 Angstroms to 2500 Angstons are formed by sputtering Mo, Cr, Al, Cu, W, Au/Cr, etc., the electrode width being set at 5 micro-metres to 10 micro-metres.
  • the SiO films 7a, 7b serve as layers to align the molecules of the liquid crystal material 6, and are formed by oblique deposition in a direction parallel to the associated metal electrode and in a direction at an angle of 58° to 64° relative to the normal of the associated substrate.
  • a TN liquid crystal material is employed in this embodiment, although a ferro-electric liquid crystal material may also be used.
  • the insulating films 5 are formed by physical vapour deposition, (i.e. sputtering, vapour deposition ion plating), so that the thickness of the insulating films 5 becomes the same over the whole substrate. In the case of the liquid crystal device having a minute gap of 1.5 micro-metres to 6.0 micro-metres, formation of the insulating films by physical vapour deposition is important to make a uniform gap. Although there are as many of the insulating films 5 as there are pairs of the transparent electrodes 3a, 3b in Figure 2, it is rather preferred to provide fewer of the insulating films than the pairs of transparent electrodes.
  • the insulating films 5 are preferably disposed with a pattern spacing of 100 micro-metres to 1000 micro-metres.
  • the trains of the metal electrodes 4a, 4b formed on both glass substrates 1a, 1b should intersect at right angles, so that the positioning of the electrodes is facilitated and the liquid crystal device, including lead out electrode sections, is made compact.
  • the dimensions of the insulating films 5 are (5 micro-metres to 10 micro-metres) x (5 micro-metres to 10 micro-metres).
  • Figure 3 is a diagram of the overall liquid crystal device comprising lead out electrode sections 9, a liquid crystal sealing section 10, a liquid crystal material injection opening 11 and a display area 12.
  • the liquid crystal sealing section 10 is filled with an epoxy adhesive in order to fix the glass substrates 1a, 1b with their respective electrode sections set opposite to each other.
  • the liquid crystal injection opening 11 is used to inject the liquid crystal material into the display area 12, and is sealed with epoxy resin after the liquid crystal material has been injected.
  • the display area 12 is provided with the electrode structure shown in Figures 1 and 2.
  • the lead out electrode sections 9 are provided for supplying the metal electrodes 4a, 4b with a driving voltage for the liquid crystal material.
  • the gap between electrodes in the lead out electrode sections 9 is increased to 200 micro-metres to 1000 micro-metres, because the gap between the electrodes in the display area 12 may be as little as 10 micro-metres to 20 micro-metres, which is too small for the connection of an external signal line.
  • Figure 4 is a graph showing the relation between the driving voltage and transmissivity of the liquid crystal device according to the present invention.
  • Curves 13 and 14 represent the characteristics when the thickness of the insulating films 5 is set at 1.5 micro-metres and 2.5 micro-metres, respectively.
  • the transmissivity represented in Figure 4 is measured using an argon laser beam having a wavelength of 488 nm.
  • the liquid crystal device according to the present invention is seen to have characteristics far different from those of a conventional liquid crystal device, and its transmissivity is also seen to have a sharp peak in relation to a particular driving voltage. Moreover, the position of such a peak varies with the thickness of the insulating films 5, and varies slightly also with the assembly conditions for the liquid crystal device even when the thickness of the insulating films is the same.
  • the peak position varies with the wavelength of the light used.
  • the operational driving voltage range is determined when the liquid crystal device characteristics have been evaluated one after another.
  • the liquid crystal device having the characteristics represented by the curve 13 of Figure 4 for instance, is driven by applying a driving voltage of 3.5 V while it is held on and 5.2 V while it is held off.
  • the contrast ratio of the liquid crystal device thus obtained is a value as high at 1:150 to 1:1800.
  • the SiO films 7a, 7b are formed by oblique deposition in a direction at an angle of 80° relative to the normal of the associated substrate, and the insulating films 5 are formed by sputtering SiO2 to a thickness of 2.0 micro-metres.
  • the liquid crystal device attains a contrast ratio of 1:300 to 1:2000.
  • the ferro-electric liquid crystal material may be composed of a mixture of ester type SmC liquid crystal materials with an optically active material added.
  • the mixture may comprise 4-((4′-octyl) phenyl) benzoic acid (3 ⁇ -fluoro, 4 ⁇ -octyloxy) phenyl ester: and 4-((4′-octyloxy) phenyl) benzoic acid (3 ⁇ -fluoro, 4 ⁇ -octyloxy) phenyl ester: at a ratio of 1:1.
  • the optically active material may comprise 5-octyloxynaphthalene carboxylic acid 1′-cyanoethyl ester: which is added to the above mixture by a weight of 25% to form the ferro-electric liquid crystal composition.
  • FIG. 5 is a graph illustrating the resolution characteristics of the liquid crystal device according to the present invention, wherein the spatial frequency of the resolution test chart is indicated on the abscissa and the OTF is indicated on the ordinate.
  • the curves 15, 16 and 17 represent the characteristics when transparent electrodes sized 5 micro-metres x 5 micro-metres, 10 micro-metres x 10 micro-metres and 20 micro-metres x 20 micro-metres are used, respectively.
  • the wavelength of the light used for the evaluation of the resolution was 488 nm.
  • the resolution of the liquid crystal device according to the present invention increases sharply as the size of the transparent electrodes is made smaller. Moreover, the good contrast ratio of the liquid crystal device prevents the OTF from decreasing drastically even when the size of the transparent electrode is decreased. In this way, the liquid crystal device according to the present invention is seen to have a resolution of 20 lp/mm to 100 lp/mm.
  • the liquid crystal device is generally designed as a spatial light modulator for use in controlling the wave front of optical data very often having good coherence, distortion of the wave front of the light passing through the liquid crystal spatial light modulator has to be removed as it greatly impairs the performance of the optical operations. Differences between images using the liquid crystal device according to the present invention were calculated. As a result, it was found that the flatness variation of each glass substrate had to be not greater than 0.05 micro-metres in order to carry out uniform calculation of the differences over the whole display area of the liquid crystal device.
  • the flatness of a glass substrate may have an inferior value when a laser beam source such as an He-Ne laser, a YAG laser or a semi-conductor laser having a wavelength longer than 488 nm is employed.
  • a laser beam source such as an He-Ne laser, a YAG laser or a semi-conductor laser having a wavelength longer than 488 nm is employed.
  • the flatness of the glass substrate was expected to affect the unevenness of contrast in the liquid crystal device, almost no unevenness of contrast was found when the flatness of the glass substrate varied by no more than 0.05 micro-metres.
  • the liquid crystal device according to the present invention uses metal electrodes, its aperture ratio tends to become low so that it is apt to provide an extremely dim liquid crystal spatial light modulator.
  • the aperture ratio may be rendered as large as 45% to 60% by making the linear width of the electrodes 5 micro-metres to 10 micro-metres, which gives a similar aperture ratio by comparison with that of a conventional liquid crystal device.
  • Figure 6 is a graph illustrating the relation between the reflectivity and the contrast ratio of the dielectric multi-layer film mirrors used in the liquid crystal device according to the present invention. As is obvious from Figure 6, the contrast ratio is seen to improve sharply when the reflectivity of the dielectric multi-layer film mirror exceeds approximately 60% and proves satisfactorily usable when the reflectivity is over 50%.
  • the liquid crystal device according to the present invention exhibits a resolution of 10 lp/mm to 100 lp/mm at a contrast ratio of 1:100 to 1:1000, and the liquid crystal spatial optical modulator shows minimum wave front distortion after laser beam modulation, whereby it proves very effective in processing optical data such as in image processing and optical computing.
  • the liquid crystal device according to the present invention is effective in processing optical data on receiving electrical data to be processed and is effectively applicable to matched filter using Computer Generated Holograms (CGHs).
  • CGHs Computer Generated Holograms

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mathematical Physics (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Geometry (AREA)
  • Liquid Crystal (AREA)
EP89312169A 1988-11-29 1989-11-23 Liquid crystal device for providing a spatial light modulator for modulating a laser beam Expired - Lifetime EP0371695B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP63302020A JPH02146526A (ja) 1988-11-29 1988-11-29 液晶素子
JP302020/88 1988-11-29

Publications (3)

Publication Number Publication Date
EP0371695A2 EP0371695A2 (en) 1990-06-06
EP0371695A3 EP0371695A3 (en) 1990-12-19
EP0371695B1 true EP0371695B1 (en) 1995-02-01

Family

ID=17903931

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89312169A Expired - Lifetime EP0371695B1 (en) 1988-11-29 1989-11-23 Liquid crystal device for providing a spatial light modulator for modulating a laser beam

Country Status (5)

Country Link
US (1) US5168383A (ko)
EP (1) EP0371695B1 (ko)
JP (1) JPH02146526A (ko)
KR (1) KR0143420B1 (ko)
DE (1) DE68920976T2 (ko)

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US5381253A (en) * 1991-11-14 1995-01-10 Board Of Regents Of University Of Colorado Chiral smectic liquid crystal optical modulators having variable retardation
US5552912A (en) * 1991-11-14 1996-09-03 Board Of Regents Of The University Of Colorado Chiral smectic liquid crystal optical modulators
TW245772B (ko) * 1992-05-19 1995-04-21 Akzo Nv
EP0571022A1 (en) * 1992-05-19 1993-11-24 Akzo Nobel N.V. Fabry-perot with coated mirrors
GB9224542D0 (en) * 1992-11-24 1993-01-13 Secr Defence Ferroelectric liquid crystal device
US5425115A (en) * 1994-07-18 1995-06-13 Martin Marietta Corporation Polarization insensitive optical switch
US5627666A (en) * 1994-07-27 1997-05-06 Board Of Regents Of The University Of Colorado Liquid crystal phase modulator using cholesteric circular polarizers
JP3047311B2 (ja) * 1994-12-08 2000-05-29 キヤノン株式会社 液晶表示装置
US5781268A (en) * 1996-04-09 1998-07-14 Board Of Regents Of The University Of Colorado Polarization-insensitive fabry-perot tunable filter
US6211993B1 (en) 1996-05-20 2001-04-03 Nz Applied Technologies Corporation Thin film ferroelectric light modulators
TW409192B (en) * 1996-07-23 2000-10-21 Ibm A spatial light modulator and a method of assembling the same
US6292243B1 (en) 1996-09-02 2001-09-18 Seiko Epson Corporation Two-layer liquid crystal panel having a polymer liquid crystal layer and equipment using the same
US6839108B1 (en) * 1998-05-16 2005-01-04 Semiconductor Energy Laboratory Co., Ltd. Liquid crystal display device and method of manufacturing the same
US6795147B1 (en) * 2000-01-14 2004-09-21 Microsoft Corporation Contrast enhancement for transmissive display systems
US6954253B2 (en) * 2000-07-25 2005-10-11 Scientific Solutions, Inc. Optical multiplexer and cross-switch using etched liquid crystal fabry-perot etalons
US6643054B1 (en) * 2001-01-22 2003-11-04 Carl-Zeiss-Stiftung Beam deflector, switching system comprising beam deflectors as well as method for selectively coupling terminals for optical signals
GB2383886B (en) * 2001-12-20 2005-07-20 Corning Inc Spatial light modulators with improved inter-pixel performance
US20040046908A1 (en) * 2002-09-10 2004-03-11 Toppoly Optoelectronics Corp. Liquid crystal display device with multiple dielectric layers
AU2005269256B2 (en) * 2004-08-03 2008-08-07 Silverbrook Research Pty Ltd Head mounted display with wave front modulator
US8574823B2 (en) * 2005-10-05 2013-11-05 Hewlett-Packard Development Company, L.P. Multi-level layer
TWI274905B (en) * 2006-03-16 2007-03-01 Wintek Corp Color filter
US20080043166A1 (en) * 2006-07-28 2008-02-21 Hewlett-Packard Development Company Lp Multi-level layer
KR20160061548A (ko) * 2014-11-21 2016-06-01 삼성디스플레이 주식회사 어레이 테스트 모듈레이터 및 이를 포함하는 박막트랜지스터 기판 검사 장치
KR101866951B1 (ko) * 2016-02-26 2018-06-12 주식회사 자연과사람 주변 환경 적응 구조의 전자기기의 액정 스크린
JP2023549638A (ja) * 2020-10-29 2023-11-29 シューラット テクノロジーズ，インク． 共振ベースのライトバルブシステム

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Also Published As

Publication number Publication date
JPH02146526A (ja) 1990-06-05
EP0371695A2 (en) 1990-06-06
EP0371695A3 (en) 1990-12-19
KR900008314A (ko) 1990-06-03
KR0143420B1 (ko) 1998-07-15
US5168383A (en) 1992-12-01
DE68920976T2 (de) 1995-05-24
DE68920976D1 (de) 1995-03-16

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